Deletion of guanine nucleotide binding protein az subunit in mice induces a gene dose dependent tolerance to morphine

The Mechanism Underlying the development of tolerance to morphine, is still incompletely understood. Morphine binds to opioid receptors, Which in turn activates downstream second messenger cascades through heterotrimeric guanine nucleotide binding proteins (G proteins). In this paper, we show that G(z), a member of the inhibitory G protein family, plays an important role in mediating the analgesic and lethality effects of morphine after tolerance development. We blocked signaling through the G(z) second messenger cascade by genetic ablation of the alpha subunit of the G protein in mice. The Galpha(z) knockout Mouse develops significantly increased tolerance to morphine. which depends oil Galpha(z), gene dosage. Further experiments demonstrate that the enhanced morphine tolerance is not caused by pharmacokinetic and behavioural learning mechanisms. The results suggest that G(z) signaling pathways are involved ill transducing the analgesic and lethality effects of morphine following chronic morphine treatment. (C) 2004 Elsevier Ltd. All rights reserved.

Between the input and the acquisition lies the shadow

Acquisition by Processing Theory (APT) is a unified account of language processing and learning that encompasses both L1 and L2 acquisition. Bold in aim and broad in scope, the proposal offers parsimony and comprehensiveness, both highly desirable in a theory of language acquisition. However, the sweep of the proposal is accompanied by an economy of description that makes it difficult to evaluate the validity of key learning claims, or even how literally they are to be interpreted. Two in particular deserve comment; the first concerns the learning mechanisms responsible for adding new L2 grammatical information, and the second the theoretical and empirical status of the activation concept used in the model.

A learning approach for performance evaluation of local network

In this paper, a novel approach is developed to evaluate the overall performance of a local area network as well as to monitor some possible intrusion detections. The data is obtained via system utility 'ping' and huge data is analyzed via statistical methods. Finally, an overall performance index is defined and simulation experiments in three months proved the effectiveness of the proposed performance index. A software package is developed based on these ideas.